ISLAMABAD - Muhammad Shahid Nazir is a testament to the age-old adage that if you give a man a fish, he will eat for a day, but if you teach a man to sing about fish, his song will shoot up the British pop chart.

The 31-year-old Pakistani fishmonger catapulted to fame in recent weeks in the unlikeliest of circumstances: while hawking frozen snapper and mackerel for one British pound ($1.61) at Queens Market in London.

Not comfortable with shouting about his merchandise to attract customers, as many vendors do, he came up with a simple ditty that someone caught on video and posted on YouTube earlier this year. It became a viral sensation and has been viewed over 7 million times.

“One Pound Fish changed my whole life,” said Nazir, who returned to Pakistan on Thursday to a hero’s welcome and has been inundated with requests to perform and do advertisements. “I am so happy now.”

To describe the song as catchy would be a gross understatement. It drills deep into your brain and sits like a lyrical jack-in-the box that goes off every few minutes, causing one to break into song involuntarily to the amusement, or perhaps growing despair, of those nearby.

“Come on ladies, come on ladies, one pound fish! Have a, have a look, one pound fish!” sings Nazir, as he points to his wares behind him. “Very, very good, one pound fish! Very, very cheap, one pound fish!”

In an era in which the Internet seems to bestow almost everyone with 15 minutes of fame, Nazir’s YouTube video could have been the end of the story. But Warner Music offered Nazir a deal to record a techno-infused version of One Pound Fish, he said. In a Bollywood-style video, he performs in a snazzy suit alongside scantily-clad dancers to a South Asian-influenced pop beat.

The music video has been viewed nearly 9 million times since it was posted on YouTube about three weeks ago. As the song gained momentum, people began talking about it as a serious contender for the fabled No. 1 Christmas single in the United Kingdom — the song that tops the chart in the week the holiday falls. Past chart-toppers include The Beatles’ I Want to Hold Your Hand and Whitney Houston’s I Will Always Love You.

In the end, One Pound Fish made it to No. 29 on the top-40 chart. It was beaten by another Internet sensation, PSY’s Gangnam Style, which clocked in at No. 6. The No. 1 spot was clinched by a version of the Hollies’ He Ain’t Heavy, He’s My Brother by The Justice Collective, a group of star musicians who recorded the charity single for victims of a stampede at a soccer stadium in 1989 that killed 96 people.

Nazir definitely doesn’t view missing out on the No. 1 Christmas single as a setback. He has returned to his home country to get a visa for France for the release of his hit song there and also has plans to take One Pound Fish to the United States, where he hopes it will make a big splash.

It has been quite a ride. He grew up in the little-known town of Pattoki near the eastern city of Lahore. His father owned a transport company, but his passion was always music, and he spent his youth singing both religious songs and pop hits by stars like Michael Jackson.

He travelled to Britain to study but eventually got a work permit and started working as a fishmonger in London nine months ago, he said. He now wants to pursue a career in music, but the fish stall in London will always hold a special place in his heart.